diff --git a/src/openrct2/localisation/StringIds.h b/src/openrct2/localisation/StringIds.h
index a8a62267d3..fe005f4b9a 100644
--- a/src/openrct2/localisation/StringIds.h
+++ b/src/openrct2/localisation/StringIds.h
@@ -12,8 +12,8 @@
 
 #include "../common.h"
 
-#define STR_NONE ((rct_string_id)-1)
-#define STR_VIEWPORT ((rct_string_id)-2)
+constexpr const rct_string_id STR_NONE = 0xFFFF;
+constexpr const rct_string_id STR_VIEWPORT = 0xFFFE;
 
 enum
 {